the whole cam failures are wildly exaggerated. if it was such a problem we would be hearing about it on the regular, like somebody would be posting at least once a week. does it happen? yes. are there bad parts out there? absolutely! should that dissuade you from using a flat tappet? i don't think so.
you have a pretty decent base to work with. performer and a 670 isn't a world beater, but those are perfectly cromulent parts to make a nice little hot rod. throw a set of dougs on there and splash the pot with some heads and you'll be cooking.
i would totally scoop that for future shenanigans.
oh, here's the dirty secret: they DID use professional drivers! and... the cars were straight heaters!